Use the interactive map below to check population changes. Zoom in to see where Podocnemis unifilis is Endangered based on IUCN Red List criteria - A3bd.
- Overall Podocnemis unifilis is Endangered based on future population size reduction criteria. The adult female population is predicted to decline by 58.3% in the future (25 and 75% quantile range: 59 - 57.6 % decline).
Map
Due to the number of points, the map can become slow to respond when you zoom in. Zoom out to a level showing fewer points and you can pan around the map to find the area of interest. Then zoom in again to check the coloured points.
If you find any errors (e.g. points where Podocnemis unifilis does not nest) please raise an issue at: https://github.com/darrennorris/testmap/issues .
When you zoom in you will see shaded points. The points follow rivers produced by remote sensing (Free-flowing Rivers, 2019: https://doi.org/10.1038/s41586-019-1111-9). To facilitate online viewing the mapped points are a subset at intervals of approximately 10 kilometers. The points are brown where populations are predicted to decline by 50% or more within 3 generations (42 years). Brown points therefore represent rivers where the species is Endangered, following the IUCN Red List population size reduction criteria - A3bd (https://www.iucnredlist.org/about/faqs).
Methods
The analysis is developed here: https://github.com/darrennorris/TACAR, and is an extension of Norris et. al. 2019 that includes:
- Stochastic population projections.
- Future impacts to populations caused by human acessibility (hunting) and actions that reduce river connectivity.
Summaries
A summary of the map results is presented below. This includes summaries by country and major basin using the full set of points at 1 kilometer intervals. Results include the size and extent of future population changes. The column “population change” is the difference in the number of adult females after 3 generations (42 years). This is consistent with the population sze reduction criteria used by the IUCN Red List. The column “River length Endangered”, is the proportion of river length where populations declined by 50% or more, and represents the spatial extent of future changes.
Summary by country.
| Country | Population change | River length Endangered (prop) | River length (km) |
|---|---|---|---|
| Bolivia | -0.58 (-0.58 – -0.57) | 0.70 | 22217 |
| Brazil | -0.63 (-0.63 – -0.62) | 0.74 | 190555 |
| Colombia | -0.48 (-0.49 – -0.48) | 0.63 | 38552 |
| Ecuador | -0.78 (-0.79 – -0.77) | 0.85 | 8302 |
| French Guiana | -0.48 (-0.5 – -0.46) | 0.63 | 3298 |
| Guyana | -0.25 (-0.26 – -0.23) | 0.45 | 7372 |
| Peru | -0.68 (-0.69 – -0.68) | 0.78 | 47363 |
| Suriname | -0.26 (-0.28 – -0.24) | 0.46 | 5756 |
| Venezuela | -0.38 (-0.39 – -0.38) | 0.56 | 30022 |
| Total | 353437 |
Summary by basin.
In the table below “Amazon” includes the Amazon Basin together with the Araguaia-Tocantins Basin in Brazil. “Coastal North” covers the Guianas and includes the Essequibo Basin. “Coastal South” includes part of Maranhão State in Brazil.
| Basin | population change | River length Endangered (prop) | River length (km) |
|---|---|---|---|
| Amazon | -0.606 (-0.61 – -0.6) | 0.72 | 280121 |
| Coastal North | -0.339 (-0.35 – -0.33) | 0.52 | 20835 |
| Coastal South | -0.973 (-0.97 – -0.97) | 1.00 | 6467 |
| Orinoco | -0.501 (-0.51 – -0.49) | 0.64 | 46014 |
Summary by major basins and countries.
| Basin | Country | population change | River length Endangered (prop) | river length (km) |
|---|---|---|---|---|
| Amazon | Bolivia | -0.58 (-0.58 – -0.57) | 0.70 | 22217 |
| Amazon | Brazil | -0.62 (-0.62 – -0.61) | 0.73 | 180434 |
| Amazon | Colombia | -0.35 (-0.36 – -0.34) | 0.53 | 18687 |
| Amazon | Ecuador | -0.78 (-0.79 – -0.77) | 0.85 | 8302 |
| Amazon | Guyana | -0.98 (-0.98 – -0.98) | 1.00 | 423 |
| Amazon | Peru | -0.68 (-0.69 – -0.68) | 0.78 | 47363 |
| Amazon | Venezuela | 0.07 (0.05 – 0.09) | 0.22 | 2695 |
| Coastal North | Brazil | -0.52 (-0.54 – -0.49) | 0.66 | 3653 |
| Coastal North | French Guiana | -0.48 (-0.5 – -0.46) | 0.63 | 3297 |
| Coastal North | Guyana | -0.2 (-0.22 – -0.19) | 0.41 | 6928 |
| Coastal North | Suriname | -0.26 (-0.28 – -0.24) | 0.46 | 5756 |
| Coastal North | Venezuela | -0.59 (-0.62 – -0.56) | 0.72 | 1201 |
| Coastal South | Brazil | -0.97 (-0.97 – -0.97) | 1.00 | 6466 |
| Orinoco | Colombia | -0.61 (-0.61 – -0.6) | 0.72 | 19865 |
| Orinoco | Venezuela | -0.42 (-0.43 – -0.41) | 0.58 | 26126 |
The table values can also be presented graphically. This enables a more comprehensive understanding of the patterns.
Population changes across basins and contries
The bars in the graph above show predicted population changes for each basin country combination. The background shading follows a gradient from Near Threatened (-0.2 is 20% loss) to Critically Endangered (-0.8 is 80% loss). The width of the bars is proportional to the river length on a log scale. The labels above each bar show river lengths in thousands of kilometers (e.g. 22.2 is 22,200 kilometers).